Rotor wing aircraft having an adjustable tail nozzle

ABSTRACT

Aircraft including an airframe having a fuselage extending between a forward end and an aft end and a fixed wing extending laterally from the fuselage. The aircraft includes a power plant mounted on the airframe producing exhaust during operation. The aircraft includes a rotor/wing rotatably mounted on the airframe including a plurality of blades and an adjustable nozzle mounted on the airframe downstream from the power plant exhaust for selectively directing the power plant exhaust to exit the aircraft at a pre-selected angle with respect to the airframe within a range of angles extending from about horizontally rearward to about vertically downward.

BACKGROUND OF THE INVENTION

The present invention relates to aircraft and, more particularly, torotor-wing aircraft having an adjustable tail nozzle.

The rotor/wings or blades of conventional rotary wing or rotor-wingaircraft are frequently driven by a rotating shaft or mast that rotatesabout a generally vertical axis. The rotating blades and shaft cause areaction torque that is frequently counter-balanced by smaller rotorblades mounted on the aircraft tail so they rotate about a generallyhorizontal axis. In other cases, the reaction torques arecounter-balanced by having two counter-rotating main rotor blade sets.In order to avoid the problems associated with reaction torques, somerotary wing aircraft are reaction driven. That is, the rotor/wings arerotated by high-pressure gas exhausted from a trailing edge of eachwing. Because reaction-driven aircraft are not shaft driven, significantreaction torques are not transmitted to the aircraft body. The gasdelivered to each wing of a reaction-driven aircraft is typicallycreated by a power plant (e.g., a gas turbine engine) mounted in theaircraft body and directed to the rotor/wing through the rotor mast.

Higher performance rotor-wing aircraft are sought. If reaction-driverotor-wing aircraft are used, increasing performance generally requiresincreased exhaust mass flow rates and operating pressures. However,reaction-drive rotor-wing aircraft have significant system losses.Reaction-drive rotor-wing aircraft also require a relatively thick rotormast and relatively large rotor blades to accommodate the exhaustpassing through them during aircraft operation. In addition, heavy metalparts are required for transferring the high-temperature exhaust fromthe power plant to the blade tips. Further, the larger mast and bladesincrease aircraft weight and drag, requiring even larger power plants,which increase fuel usage and cost.

In addition, there is a need for increased vertical thrust duringvertical flight of rotor-wing aircraft. One method for providing morethrust is to provide a second rotor/wing. Another method for providingmore thrust is to provide a vertical fan in the aircraft. However,adding a second rotor/wing or adding a vertical fan greatly increasesthe complexity of the required drive train, manufacturing cost, and theweight of the aircraft. A rotor-wing aircraft design is sought that ismore efficient than conventional reaction-drive rotor-wing aircraft andprovides increased vertical thrust.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to aircraft including an airframe having afuselage extending between a forward end and an aft end and a fixed wingextending laterally from the fuselage. The aircraft also includes apower plant mounted on the airframe producing exhaust during operation.In addition, the aircraft includes a rotor/wing rotatably mounted on theairframe including a plurality of blades and an adjustable nozzlemounted on the airframe downstream from the power plant exhaust forselectively directing the power plant exhaust to exit the aircraft at apre-selected angle with respect to the airframe within a range of anglesextending from about horizontally rearward to about vertically downward.

In another aspect, the present invention relates to a method ofoperating aircraft having an airframe, a power plant mounted on theairframe, a rotor including a plurality of blades extending radiallyoutward from a drive shaft that is rotatably mounted on the airframe,and an adjustable nozzle mounted on the airframe downstream from thepower plant. The method includes producing exhaust using the power plantand directing the exhaust from the power plant to the adjustable nozzle.In addition, the method includes selectively directing the power plantexhaust to exit the aircraft at a pre-selected angle with respect to theairframe within a range of angles extending from about horizontallyrearward to about vertically downward by adjusting the nozzle.

Other aspects of the present invention will be in part apparent and inpart pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of an aircraft according to the presentinvention.

FIG. 2 is a side view of the aircraft according to the presentinvention.

FIG. 3 is a perspective of a radial inflow turbine of the aircraftaccording to the present invention.

FIG. 4 is a perspective of the radial inflow turbine shown without halfof a body of the radial inflow turbine.

FIG. 5 is a cross section taken along lines 5-5 of FIG. 3.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the figures, and more particularly to FIG. 1, aircraftaccording to the present invention is designated in its entirety byreference number 10. The aircraft 10 has an airframe, generallydesignated by 12, which includes a fuselage 14 having a nose or forwardend 16 and a tail or aft end 18. Although the fuselage 14 may have otherlengths extending between the forward end 16 and the aft end 18 withoutdeparting from the scope of the present invention, in one embodiment thefuselage has a length of between about 60 feet and about 70 feet. Theaircraft 10 further includes at least two primary fixed wings or canards20 extending laterally from the fuselage. Each primary fixed wing 20 hasa wing tip 22 opposite the fuselage 14. Although the aircraft 10 mayhave other primary wingspans extending between the wingtips 22 withoutdeparting from the scope of the present invention, in one embodiment theaircraft has a primary wingspan of between about 35 feet and about 45feet. The aircraft 10 may also include a rear set of fixed wings 24.Each rear fixed wing 24 has a wing tip 26 opposite the fuselage 14.Although the aircraft 10 may have other rear wingspans extending betweenthe rear wingtips 26 without departing from the scope of the presentinvention, in one embodiment the aircraft has a rear wingspan of betweenabout 30 feet and about 40 feet. The fixed wings 20, 24 may fold orpivot. For example, in one embodiment each of the fixed wings 20, 24 hasa chord 28, 30 and the fixed wings are pivotally mounted on the fuselage14 for selective movement between a forward flight position, in whichthe respective chord extends generally horizontally, and a verticalflight position, in which the respective chord extends generallyvertically. The forward flight position of the fixed wings 20, 24 isshown by solid lines in FIG. 2 and generally indicated by referencearrow F and the vertical flight position is shown by dashed lines andgenerally indicated by reference arrow V. The fixed wings 20, 24 mayalso be moved to intermediate flight positions (not shown) between theforward and vertical flight positions wherein the respective wing chord28, 30 is between horizontal and vertical.

As shown in FIG. 1, the aircraft 10 further includes one or more powerplants 32, 34 mounted on the airframe. The power plants 32, 34 producepower in the form of hot high-pressure gas or exhaust during theiroperation. Although the power plants 32, 34 may produce other amounts ofpower without departing from the scope of the present invention, in oneembodiment the power plants produce between about 11,000 pounds andabout 13,000 pounds of thrust. Although other power plants 32, 34 may beused without departing from the scope of the present invention, in oneembodiment each power plant is a F404 Turbofan available from GeneralElectric Company of Cincinnati, Ohio. The aircraft 10 also includes atleast one rotor/wing, generally designated by 36, rotatably mounted onthe aircraft by way of a drive shaft 38. The rotor/wing 36 includes aplurality of blades 40 extending radially from a central hub 42 that isconnected to the drive shaft 38 to a blade tip 44. In one embodiment,the rotor/wing 36 has two primary blades 40 extending from the hub 42 inopposite directions from each other. Although the blades 40 may haveother lengths between the hub 42 and the respective blade tips 44, inone embodiment each blade has a length of between about 30 feet andabout 35 feet. Because the blades 40 and the drive shaft 38 do not needto be configured for routing exhaust, the blades and drive shaft can bethinner and lighter than the blades and rotor mast of reaction-driverotor-wing aircraft. The reduced weight and drag characteristics of therotor/wing 36 improves aircraft 10 performance and lowers powerrequirements compared to reaction-drive systems. Although the blades 40may have other maximumn thicknesses 46 without departing from the scopeof the present invention, in one embodiment each blade has a maximumthickness of between about 1 foot and about 2 feet. Although the rotorblades 40 may be made of other materials, in one embodiment at least aportion of the blades are made of a polymer composite.

The aircraft 10 has a rotation mode wherein the rotor/wing 36 is rotatedby the power plants 32, 34 and a fixed mode wherein the rotor/wing islocked to prevent rotor/wing rotation. In the rotation mode, therotor/wing 36 rotates to provide upward thrust to the aircraft 10. Theprimary fixed wings 20 are moved to their vertical flight position Vwhen the aircraft 10 is in the rotation mode so the primary fixed wingsminimally interfere with rotor 36 downwash and thus minimally inhibitthe production of upward thrust by the rotor. The rear fixed wings 24are also rotated to their vertical flight position when the aircraft 10is in the rotation mode so they minimally inhibit upward propulsion. Inthe fixed mode, the rotor/wing 36 is locked so the blades 40 extendlaterally to provide aerodynamic lift to the aircraft 10 during forwardflight. The aircraft 10 may also fly at intermediate flight modeswherein the aircraft is propelled at an angle between vertical andhorizontal. For example, an aircraft 10 transitioning between verticaland horizontal flight will fly at angles between vertical andhorizontal. The fixed wings 20, 24 are moved to their forward flightpositions F when the aircraft 10 is in the fixed mode and can assumeintermediate flight positions corresponding to intermediate flightmodes.

The aircraft 10 also includes a radial inflow turbine, generallydesignated by 48, mounted on the airframe 12 in fluid communication withthe power plants 32, 34 for receiving exhaust from the power plants. Theradial inflow turbine 48 is mechanically connected to the rotor/wing 36and converts exhaust from the power plants 32, 34 to mechanical powerfor rotating the rotor/wing during operation of the aircraft 10. Lossesincurred in converting the exhaust to mechanical power for rotating therotor/wing 36 are generally lower than the losses incurred between thepower plant(s) and the rotor/wing in a conventional reaction-driverotor/wing system. The higher efficiency of the radial inflow turbine 48system according to the present invention enables high performance anduses less power than is required for reaction-drive systems. As shown inFIG. 3, the radial inflow turbine 48 includes a body or housing 50forming a first inlet 52 and a second inlet 54. As shown in FIG. 1, thefirst and second inlets 52, 54 are in fluid communication with the firstand second power plants 32, 34, respectively. The turbine body 50 alsoforms a first aft outlet 56 and a second aft outlet 58 downstream fromthe first and second inlets 52, 54, respectively.

In addition, the turbine body 50 forms an annular vertical plenum orchamber 60 in fluid communication with the inlets 52, 54 and outlets 56,58. As shown in FIG. 4, the vertical chamber 60 has an upper portion 62and a lower portion 64. Although the upper portion 62 of the verticalchamber 60 may have other minimum radii 66 without departing from thescope of the present invention, in one embodiment the upper portion hasa minimum radius of between about 20 inches and about 22 inches.Although the lower portion 64 of the vertical chamber 60 may have othermaximum radii 68 without departing from the scope of the presentinvention, in one embodiment the lower portion has a maximum radius ofbetween about 7 inches and about 9 inches. The radial inflow turbine 48further includes a chamber outlet 70 downstream from the verticalchamber 60. Exhaust from the power plants 32, 34 passing through thevertical chamber 60 exits the radial inflow turbine 48 with reducedenergy by way of the chamber outlet 70. Upon exiting the chamber outlet70, the exhaust flows into a low-energy conduit 72, as shown in FIG. 1.

The radial inflow turbine 48 also includes a hub 74 rotatably connectedto the turbine body 50 and a plurality of vanes 76 extending radiallyoutward from the hub. The hub 74 and the vanes 76 are positioned in theturbine vortical chamber 60. Each of the vanes 76 includes a top 78positioned in the upper portion 62 of the vortical chamber 60 and abottom 80 positioned in the lower portion 64 of the vortical chamber.Each vane 76 is pitched from its top 78 to its bottom 80. As will beappreciated by those skilled in the art, the pitch of the vanes 76creates an oblique surface 82 against which power plant 32, 34 exhaustis directed to cause the vanes 76 and hub 74 to rotate during operationof the aircraft 10 in the rotation mode. In one embodiment, each vane 76has a maximum radius 84 corresponding to the minimum radius 66 of theupper portion 62 of the vortical chamber 60 and a minimum radius 86corresponding to the maximum radius 68 of the lower portion 64 of thevortical chamber. The radial inflow turbine 48 further includes aturbine shaft 88 operatively connected to the turbine hub 74 and to therotor/wing drive shaft 38. In one embodiment, the rotor/wing drive shaft38 and the turbine shaft 88 are integrally formed. The turbine hub 74,the vanes 76, and the turbine shaft 88 rotate together and therotor/wing 36 is rotated by torque received from the turbine shaftduring operation of the aircraft 10.

As shown in FIG. 1, the aircraft 10 may include a gearbox 90 connectedto the turbine shaft 88 and the rotor/wing drive shaft 38 fortransmitting power transferred from the turbine shaft to the driveshaft. In one embodiment, the gearbox 90 is a reduction gearbox forreducing the power and rotational speed imparted to the drive shaft 38from the turbine shaft 88. In one embodiment, the gearbox 90 is aplanetary gearbox. Although other types of gearboxes 90 may be usedwithout departing from the scope of the present invention, in oneembodiment the gearbox is an accessory gearbox available from NorthstarAerospace Inc. of Bedford Park, Ill. The gearbox 90 may have one or morestages and although the gearbox 90 may have other reduction ratioswithout departing from the scope of the present invention, in oneembodiment the gearbox has a reduction ratio of between about 7:1 andabout 9:1.

As shown in FIGS. 4 and 5, the radial inflow turbine 48 further includesan inlet valve 92, 94 positioned within the turbine body 50 adjacent toeach inlet 52, 54. Although the inlet valves 92, 94 may be other typeswithout departing from the scope of the present invention, in oneembodiment each valve is a butterfly valve (also known as a sliding doorvalve) or a ball valve. The inlet valves 92, 94 selectively allow powerplant 32, 34 exhaust to pass through the radial inflow turbine 48 fromthe respective inlet 52, 54 to the corresponding aft outlet 56, 58 forhigh-speed flight in the fixed mode or direct the exhaust through thevortical chamber 60 for flight in the rotation mode. For directing powerplant 32, 34 exhaust through the vortical chamber 60, the exhaust isfirst diverted from the respective inlet 52, 54 generally upward intothe upper portion 62 of the vortical chamber 60 by the respective inletvalve 92, 94, then the exhaust flows generally radially inward in thevortical chamber and generally downward through the vortical chamber andagainst the oblique surfaces 82 of the vanes 76, as shown by arrow E inFIG. 5. Because of the radially inward entry of the exhaust into thevortical chamber 60, this type of radial inflow turbine 48 is referredto as a radial inflow turbine. As described above, the exhaust flowingagainst the oblique surfaces 82 of the vanes 76 causes the vanes andturbine hub 74 to rotate thereby rotating the turbine shaft 88, thedrive shaft 38, and the rotor/wing 36.

For embodiments having a single power plant (not shown), the radialinflow turbine 48 can be configured in a variety of ways. For example,the turbine 48 may include a sole inlet positioned at about a center ofan upstream end of the turbine for transferring exhaust from a singlepower plant to the vortical chamber and a sole outlet positioned atabout a center of a downstream end of the turbine. It is contemplatedthat in one embodiment (not shown), the exhaust from two or more powerplants are combined upstream from the turbine and enter the turbinethrough a sole turbine inlet.

As shown in FIGS. 1 and 2, the aircraft 10 further comprises a nozzle 96mounted on the airframe 12 adjacent to the aft end 18 of the fuselage14. The nozzle 96 is in fluid communication with the power plants 32, 34for receiving exhaust. The nozzle 96 may be operatively connected toeach aft outlet 56, 58 of the radial inflow turbine 48 for receivingpower plant 32, 34 exhaust exiting the aft outlets for high-speed flightin the fixed mode. For example, a high-energy conduit 98 (shown inFIG. 1) may connect the aft outlets 56, 58 to the nozzle 96. The nozzle96 may also be operatively connected to the chamber outlet 70 forreceiving exhaust during aircraft 10 operation. For example, theaircraft 10 may further comprise a conduit valve 100 for selectivelydiverting exhaust flowing through the low-energy conduit 72 to thehigh-energy conduit 98 and to the nozzle.

The nozzle 96 may be adjustable between multiple positions to providethrust in various directions. In one embodiment, the nozzle 96selectively directs exhaust to exit the aircraft 10 at a pre-selectedangle E (shown in FIG. 2) with respect to the airframe 12 within a rangeof angles extending from about horizontally rearward (i.e., θ is about0°), as shown by solid lines, and about vertically downward (i.e., θ isabout 90°), as shown by dashed lines. When the nozzle 96 is angledrearward, the exhaust exiting the aircraft 10 provides forward thrustand when the nozzle is angled downward, the exhaust provides upwardthrust. When the nozzle 96 is vectored to an angle θ between 0° and 90°,the exiting exhaust provides thrust between forward and upward accordingto the position of the nozzle. Aircraft 10 capable of providing verticalthrust from two locations of the aircraft are referred to as two-posteraircraft. In the present invention, two-poster characteristics arepresent in the upward thrust provided at the aft end 18 of the fuselage14 by vectoring the nozzle 96 to an angle θ greater than zero and by therotor/wing 36. Two-poster aircraft 10 have enhanced flight performanceabilities compared to single-poster aircraft because they can operatewith a wider variety of centers of gravity by controlling the amount ofvertical thrust produced at each poster. For embodiments of the aircraft10 comprising multiple power plants 32, 34 and corresponding turbineinlets 52, 54 and aft outlets 56, 58, the aircraft may include aseparate nozzle (not shown) in fluid communication with each aft outlet.

As shown in FIG. 1, the aircraft 10 also comprises a yaw control system,generally designated by 102, mounted on the airframe 12 adjacent to theaft end 18 of the fuselage 14. The yaw control system 102 is in fluidcommunication with the power plants 32, 34 for receiving exhaust foractively controlling yaw. Specifically, the yaw control system 102 isoperatively connected to the chamber outlet 70 by way of the low-energyconduit 72 for receiving power plant 32, 34 exhaust exiting the radialinflow turbine 48 through the chamber outlet during aircraft 10operation. The yaw control system 102 may also be operatively connectedto the aft outlets 56, 58 for receiving exhaust during aircraft 10operation. For example, the conduit valve 100 may be configured forselectively diverting exhaust flowing through the high-energy conduit 98to the low-energy conduit 72 during aircraft 10 operation. Yaw controlmay be needed to control aircraft 10 yaw during operation in therotation mode. Although the yaw control system 102 may be other typeswithout departing from the scope of the present invention, in oneembodiment (not shown) the yaw control system is a NOTAR systemavailable from the Boeing Company of Chicago, Ill. NOTAR is a federallyregistered trademark of the Boeing Company. In one embodiment, the yawcontrol system 102 includes right and left lateral outlets 104, 106connected by a valve 108. The yaw control system valve 108 is controlledto selectively direct exhaust received from the low-energy conduit 72 tothe right lateral outlet 104, to the left lateral outlet 106, or to bothlateral outlets to control 10 yaw during operation of the aircraft 10.

When introducing elements of the present invention or the preferredembodiment(s) thereof, the articles “a”, “an”, “the”, and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including”, and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. An aircraft, comprising: an airframe having a fuselage extendingbetween a forward end and an aft end and a fixed wing extendinglaterally from the fuselage; a power plant operatively coupled to theairframe and producing exhaust during operation thereof; a rotor/wingrotatably coupled to the airframe and including a plurality of blades;an adjustable nozzle operatively coupled to the airframe and positionedat the aft end and operatively coupled to the power plant by a primaryexhaust duct, the adjustable nozzle being configured to receive anexhaust flow from the power plant via the primary exhaust duct and forselectively directing the power plant exhaust within a range of anglesextending from about horizontally rearward to about vertically downwardwith respect to the fuselage; and a turbine assembly operatively coupledto the airframe and to the rotor/wing, the turbine assembly beingdirectly coupled to the primary exhaust duct between the power plant andthe adjustable nozzle and selectively engageable with the exhaust flow,the turbine assembly including: a body coupled to the primary exhaustduct and having an inlet configured to receive a drive portion of theexhaust flow from the power plant; and a drive assembly at leastpartially disposed within the body and coupled to the rotor/wing, thedrive assembly being rotatable within the body about a rotation axis andconfigured to rotate the rotor/wing when subjected to the exhaust. 2.Aircraft as set forth in claim 1 wherein each of the fixed wings has achord and the fixed wing sets are pivotally mounted on the fuselage forselective movement between a forward flight position in which therespective chord extends generally horizontally and a vertical flightposition in which the respective chord extends generally vertically. 3.Aircraft as set forth in claim 1 wherein the aircraft has a rotationmode wherein the rotor/wing is rotated by the power plant and a fixedmode wherein the rotor/wing is locked to prevent rotor/wing rotation. 4.Aircraft as set forth in claim 1 wherein the turbine assembly isconfigured such that the drive portion of the exhaust flow is receivedinto the body along an approximately radial direction with respect tothe rotation axis, is deflected by the drive assembly, and exits fromthe body approximately along the rotation axis.
 5. Aircraft as set forthin claim 4 wherein the drive assembly includes a drive shaft projectingupwardly with respect to the fuselage and being connected to saidrotor/wing; and a turbine blade assembly coupled to the drive shaft androtatable about a rotation axis that projects along the drive shaft, theturbine blade assembly including a plurality of vanes that provide arotational force when subject to the exhaust.
 6. Aircraft as set forthin claim 5 wherein the rotor/wing is rotatable about the rotation axis,and wherein the body is partially disposed within the primary exhaustduct.
 7. Aircraft as set forth in claim 6 further comprising: a yawcontrol system mounted on the airframe adjacent to the aft end of thefuselage; wherein said outlet is in fluid communication with said yawcontrol system for selectively transferring exhaust to the yaw controlsystem.